pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2021; 71: 397-403

Published online April 30, 2021 https://doi.org/10.3938/NPSM.71.397

## Study of Lasing Characteristics of Passively Q-switched Nd:YAG Laser On Incidence Angle of Cr:YAG

Jaeyeol LEE, Jin Seog GWAG, Jonghoon YI*

Department of Physics, Yeungnam University, Gyeongsan 38541, Korea

Received: December 15, 2020; Revised: January 7, 2021; Accepted: February 13, 2021

### Abstract

The passive Q-switching characteristics of a Nd:YAG laser pumped by using a fiber coupled laser diode were analyzed. The pulse energy from the passively Q-switched laser was calculated as a function of the initial transmittance of the Cr:YAG saturable absorber and the reflectance of the output mirror. The ratio of the TEM$_{00}$ mode size in the Nd:YAG crystal to the TEM$_{00}$ mode size in the Cr:YAG crystal was calculated as a function of the incidence angle of the Cr:YAG crystal and the curvature of the resonator mirror. From the calculated ratio of the TEM$_{00}$ mode sizes, the pulse energy of the Q-switched laser was obtained. When the angle of incidence was changed between 20$^{\circ}$ and 70$^{\circ}$, the pulse energy was controlled to be in the range from 14 mJ to 32 mJ for a 40% initial transmittance, and in the range from 0 to 15 mJ for a 90% initial transmittance.

Keywords: Lasers, Q-switching, Pulse energy